Reading an OCT image- The Basics - Topcon · 2019. 10. 10. · OCT is able to see the intricate and...

Reading an OCT image- The Basics

What we will cover

• How OCT works • Layers of the retina • 3D OCT Tips • Healthy retina architecture • Pathology • Q&A

Seeing better with OCT

Light passing through tissue is delayed before it is reflected back to the camera

Measurement of this ‘delay’ provides

cross-sectional information about the structure of the tissue

being imaged

OCT is able to see the intricate and delicate layers of the retina, optic nerve and other ocular tissues (e.g. the RPE).

OCT image of the retina

Topcon 3D OCT 1000 Image

Layers of the Retina

Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004

Layers of the Retina

Nerve Fibre Layer Ganglion Cell Layer Inner Plexiform Layer Inner Nuclear Layer Outer Plexiform Layer Outer Nuclear Layer Ex. Limiting Membrane Photoreceptor IS/OS

Retinal Pigment Epithelium

Topcon 3D OCT 2000 Image

3D OCT Tips

• Trade off of scanning area vs. image quality

• Typical Pre sets – 8.2 mm x 3 mm @ 1,024 x

32 b scans (better image) – 6 mm x 6 mm box @ 512

x 128 b scans (better coverage)

Scanning Protocol

Patient preparation

• Pupil size – Min pupil size is 3.7 mm – Slightly dilated pupils will improve OCT and fundus image

quality

• Dry cornea – A dry cornea will reduce the OCT image quality – Make sure that your technicians tell the patient to blink

before the capture procedure – Use drops if needed

• Fixation

Viewing Techniques

• View in Black and White to provide better contrast

• Use OCT image adjustment bar

Healthy Retinal Architecture

Healthy Retina Architecture

Nerve Fibre Layer Ganglion Cell Layer Inner Plexiform Layer Inner Nuclear Layer Outer Plexiform Layer Outer Nuclear Layer Ex. Limiting Membrane Photoreceptor IS/OS

Retinal Pigment Epithelium

Topcon 3D OCT 2000 Image

Healthy Retina Architecture

Topcon 3D OCT 1000 Image

Healthy Retina Architecture

Topcon 3D OCT 1000 Image

Pathology

Pathology

• Reported incidence of pathology detected with Topcon 3D OCT in a Lasik population during pre-treatment evaluation was 1.6%

• Typical pathologies – Epiretinal membrane – Drusen – Macular Edema – Hard Exudates – Macular Holes – Vitromacular Traction

Epiretinal Membrane

• Incidence is 6% of patients over 60 yrs*. • Appearance

– Rippling of ILM which can extend over the fovea resulting of the loss of the normal foveal contour.

*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004

Epiretinal Membrane

Topcon 3D OCT 1000 Image

Epiretinal Membrane

Topcon 3D OCT 1000 Image

Epiretinal Membrane Case 2

Topcon 3D OCT 1000 Image

Epiretinal Membrane Case 3 with Pseudo Hole

Topcon 3D OCT 1000 Image

Drusen

• Reported incidence of drusen in patients 43 to 54 was 2.2% (soft) and 3.3% (large)*

• Appearance – Localized highly reflective area under Bruch’s membrane,

you may also see a slight flattening of the foveal contour.

*Source: Beaver Dam Eye Study Ophthalmology. 2003 Oct: 109 (10): 1767-79.

Drusen

Topcon 3D OCT 1000 Image

Drusen

*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004

Drusen

*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004

Drusen

Topcon 3D OCT 2000

Macular Edema

• Appearance – Hypo echoic areas in the retina. Can be associated with

Diabetes (Diabetic Macular Edema- DME), cystic in appearance (Cystoid Macular Edema- CME)

Macular Edema

Topcon 3D OCT 2000

CME

Topcon 3D OCT 1000 Image

Hard Exudates

• Can be seen in any conditions that are associated with vascular leakage – Diabetic retinopathy – Hypertensive retinopathy

• Appearance – Focal hyper echoic areas in the ONL

Hard Exudates

Topcon 3D OCT 1000 Image

Macular Holes

• Extremely rare in patients under except you can see in the case of trauma. Various types – Lamellar (partial macular hole) – Full thickness macular hole

• Appearance – Lamellar hole- pit/opening from ILM but not down to the RPE – Full thickness macular hole- Opening down to the RPE, volcano

appeareance

Macular Hole

*Source: Optical Coherence Tomography of Ocular Diseases, Schuman, JA, et al, 2004

Macular Hole

Topcon 3D OCT 1000 Image

Vitromacular Traction (VMT)

• Extremely rare • Appearance

– Perifoveal vitreous detachment with focal adhesion to the fovea

VMT

Topcon 3D OCT 1000 Image

VMT

Topcon 3D OCT 1000 Image